Characterization of Pseudorange Errors in Hybrid LEO/MEO PNT System

The manuscript provides a comprehensive exploration of the potential offered by LEO-based positioning, specifically quantifying the errors committed in pseudorange determination across MEO, LEO and hybrid LEO-MEO constellations. The analysis systematically characterizes individual error sources, including ionospheric and tropospheric delays, as well as multipath effects, while addressing critical constraints that affect specifically LEO platforms, such as the reliance on Two-Line Elements (TLE) for orbital determination and the inherent instability resulting from the absence of on-board atomic clocks. To ensure a high degree of precision in isolating the impact of stochastic noise, the evaluation of positioning error is conducted within a vehicular operational scenario. By focusing on navigation along a predefined path, the analysis adopts a one-dimensional (1D) model, which reduces the dimensionality of the problem. The findings demonstrate that transitioning from TLE to Precise Orbit Determination (POD) and clock stability are essential for LEO augmentation. Moreover, the results provide an analytical framework for resilient Positioning, Navigation and Timing (PNT) applications, including autonomous driving and smart cities. The ultimate objective of the manuscript is to pave the way for a new generation of localization services, capable of maintaining high-integrity positioning in scenarios where signal degradation was previously considered inevitable.